25. The difference between the tertiary
and quaternary levels of protein structure is that a tertiary level protein
is one polypeptide chain with a complex, 3-D globular shape while a quaternary
level protein is composed of 2 or more complex polypeptide chains which are
bonded together to make a larger, globular protein.
The figure on the right is a tertiary
level protein (1 complexly folded chain) while that on the right is a quaternary
level protein (each of the 4 chains is colored differently).
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Slichter